This invention relates to gas dynamic machines, such as turbochargers, compressors, turbines and the like and, more particularly, to a bearing and seal member or assembly for and in combination with a gas dynamic machine.
It is known in the art relating to gas dynamic machines, such as turbochargers, compressors, turbines, and the like, to provide a rotor supported in a housing on one or more oil lubricated bearings. An axial seal may be provided adjacent the bearing to control leakage of oil from the bearing into a compressor or turbine of the machine. Axial alignment of the seal with the bearing is generally required to provide proper seal operation. To accomplish this, concentric pilots or bores may be provided in the machine housing, a bearing being mounted in one of the bores and a seal member mounted in the other. The result is that close machine tolerances must be held in both the bearing and seal components and the pilot bores of the housing in order to obtain the desired concentricity. Installation and removal of the components may also be complicated and may require special tooling for servicing of the machine. An improved bearing and seal mounting was desired to improve the operation, manufacture installation and servicing of rotor bearings and seals for a gas dynamic machine.
The present invention provides a new bearing/seal member or assembly and a modified mounting in a gas dynamic machine, which accomplish the above-mentioned goals in an engine turbocharger and other similar machines.
In a first embodiment, the bearing and seal portions of the assembly are made as separate bodies provided with mating alignment portions that maintain axial alignment of the bearing and seal surfaces when the components are fixed together as an assembly. The assembly is radially positioned by a single pilot bore of the housing in which the bearing portion is mounted. Concentricity of the bearing and seal portions is thus determined only by the alignment portions of the bearing and seal bodies themselves and does not depend upon the tolerances of dual housing pilot bores. The axial positioning of the assembly is also determined by a single flange formed, in this case, as part of the seal body. Preferably, a thrust flange or thrust bearing surface is formed integrally on the bearing body, axially aligned with the bearing surface on an end opposite the seal body. If desired, the thrust flange could be separately mounted on the bearing body.
In use, the bearing and seal bodies are assembled with their bearing and seal surfaces in alignment and fixed together by fasteners prior to installation in the turbocharger housing. The assembly is then assembled into the housing with a pilot surface of the bearing portion supported in the housing pilot bore. The radial flange of the seal portion is then secured to a radial mounting face of the housing by, for example, screw fasteners to retain the assembly in place. The bearing/seal assembly is easily installed and may be easily removed without special tooling.
In an alternative embodiment, the bearing and seal portions are formed integrally in a single body. The body includes a single radial mounting flange, which carries a peripheral external pilot surface on the flange for engaging a pilot bore of a turbocharger housing to radially position the body in the housing. The mounting flange also is engagable with the housing for axially positioning and mounting the body in the housing. Preferably, a thrust flange having a thrust bearing surface is separately formed and attached to the bearing/seal body at the end adjacent the bearing portion. If desired, the thrust bearing surface could be formed integral with the bearing/seal body. The bearing portion of the body includes an inner bearing surface in which a floating bearing bushing with squeeze film damping is preferably received. Alternatively, a fixed bearing insert or a directly formed bearing material could be carried by the inner bearing surface.
These and other features and advantages of the invention will be more fully understood from the following description of certain specific embodiments of the invention taken together with the accompanying drawings.